In actuators in the prior art, roller lead screws or threaded rods with a screw-thread but no self-locking function require a brake device to generate a braking torque in order to prevent an external load from driving the actuator in a reverse direction. The generation of such a braking torque is realized by way of friction between a steel friction spring and a plastic brake torque bushing. It has been found that existing brake devices cannot ensure that the required braking torque will be generated.
In order to further increase the braking torque, those skilled in the art design steel friction springs and plastic brake torque bushings of larger diameter. However, this design has a drawback, namely that the volume of the brake device is increased, and is difficult to implement in a cramped application space.
In addition, since, in the case of a brake device in the prior art, a brake torque bushing made of plastic must be disposed in a brake housing made of aluminum, an elastic snap ring must be used to hold the brake torque bushing in place, so the assembly process is complex and the number of components is large.